To broadcast videos on your Facebook group you should enable live streaming for it.
Sometimes and for some Facebook groups live streaming is disabled by default. That might be a reason why you can't connect this destination in Wave.video.
To change this, follow these steps:
Step 1. On Facebook, select your group from the Groups list tab on the left.
Step 2. Scroll down to find the
Settings tab. Then find the
Manage Discussion section and access the
Post Formats options by clicking on the pencil icon.
Step 3. You'll see a toggle to enable live streaming. Click on it to turn it on.
Step 4. Get back to your Wave.video account and connect it to the Facebook group.